1Department of Prosthodontics, School of Stomatology, Fourth Military Medical University, Xi'an, Shaanxi 710032, PR China
2Research and Development Center for Tissue Engineering, Fourth Military Medical University, Xi'an, Shaanxi 710032, PR China
3Department of Oral and Maxillofacial Surgery, Cangzhou Center Hospital, Hebei, Cangzhou 061001, PR China
4Department of Oral Histology and Pathology, School of Stomatology, Fourth Military Medical University, Xi'an, Shaanxi 710032, PR China
5Department of Orthodontics, School of Stomatology, Fourth Military Medical University, Xi'an, Shaanxi 710032, PR China
6Department of Biology, Fourth Military Medical University, Xi'an, Shaanxi 710032, PR China